Xu, Sarah C

Purpose: Evaluate the relationship between CYP3A4 phenotype, the gene encoding the enzyme that metabolizes exogenous steroids, and the rate of steroid-induced intraocular pressure (IOP) response. Materials and Methods: Lymphocyte-derived DNA sequencing of CYP3A4 from 10073 patients was completed using the PGRN-Seq assay. Subjects with CYP3A4 intermediate metabolizer or slower phenotypes were identified and compared with controls matched by age, race, and sex. All subjects had at least 3 eye exams with at least an exam while on topical/systemic/local steroid in any body location except the eye. Patients with pre-existing glaucoma or glaucoma suspects were excluded. Results: Of the 10,073 patients, there were 63 patients who had CYP3A4 poor or intermediate metabolizer phenotype. Of the 63 patients, 22 had documented steroid use. Fifty-nine percent (13/22) of patients with CYP3A4 poor/intermediate metabolizer had a steroid-induced IOP response of 3 mm Hg or more, significantly higher compared with 23% (5/22) of matched controls (P=0.031). Although more poor/intermediate metabolizers were steroid responders, the average IOP elevation in steroid responders in both groups was similar (5.0±2.5 mm Hg in CYP3A4 poor/intermediate metabolizers compared with 4.1±2.1 mm Hg in controls, P=0.327). Family history of glaucoma was similar in both groups (7/22 vs. 8/22, P=1.0). Conclusion: Reduced CYP3A4 phenotypes may help identify patients at a higher risk of steroid-induced IOP elevation.

Glaucoma is one of the leading causes of blindness worldwide. Recent studies suggest that intraocular pressure (IOP) fluctuations, peaks, and rhythm are important factors in disease advancement. Yet, current glaucoma management remains hinged on single IOP measurements during clinic hours. To overcome this limitation, 24-hour IOP monitoring devices have been employed and include self-tonometry, permanent IOP, and temporary IOP monitoring. This review discusses each IOP measuring strategy and focuses on the recently FDA-approved contact lens sensor (CLS). The CLS records IOP-related ocular patterns for 24 hours continuously. Using the CLS, IOP-related parameters have been found to be associated with the rate of visual field progression in primary open-angle glaucoma, disease progression in primary angle-closure glaucoma, and various clinical variables in ocular hypertension. The CLS has been used to quantify blink rate and limbal strain and measure the circadian rhythm in a variety of disease states including normal-tension glaucoma and thyroid eye disease. The effects of various IOP-lowering interventions were also characterized using the CLS. CLS provides a unique, safe, and well-tolerated way to study IOP-related patterns in a wide range of disease states. IOP-related patterns may help identify patients most at risk for disease progression and assist with the development of tailored treatments.